EP3624111A1 - Corps central de cavité acoustique profonde - Google Patents

Corps central de cavité acoustique profonde Download PDF

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Publication number
EP3624111A1
EP3624111A1 EP19197404.7A EP19197404A EP3624111A1 EP 3624111 A1 EP3624111 A1 EP 3624111A1 EP 19197404 A EP19197404 A EP 19197404A EP 3624111 A1 EP3624111 A1 EP 3624111A1
Authority
EP
European Patent Office
Prior art keywords
center plug
aft
outer skin
cavity
bulkhead
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP19197404.7A
Other languages
German (de)
English (en)
Inventor
Carlos A. Lopez
Lisa K. MARTINI-SALIERS
David GAUL
Jose S. Alonso-Miralles
Keith E. Ritchie
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rohr Inc
Original Assignee
Rohr Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rohr Inc filed Critical Rohr Inc
Publication of EP3624111A1 publication Critical patent/EP3624111A1/fr
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/78—Other construction of jet pipes
    • F02K1/82—Jet pipe walls, e.g. liners
    • F02K1/827—Sound absorbing structures or liners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/04—Mounting of an exhaust cone in the jet pipe
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/161—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general in systems with fluid flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2220/00—Application
    • F05D2220/30—Application in turbines
    • F05D2220/32—Application in turbines in gas turbines
    • F05D2220/323—Application in turbines in gas turbines for aircraft propulsion, e.g. jet engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00—Function
    • F05D2260/96—Preventing, counteracting or reducing vibration or noise

Definitions

  • the present disclosure relates to an aircraft gas turbine engine exhaust nozzle deep-cavity centerbody, and more particularly to a centerbody that attenuates combustor noise and provides improved accessibility via a passage through the centerbody.
  • An airplane's airframe and engines produce varying amounts of audible noise during takeoff and landing.
  • an aircraft's engines typically operate at or near maximum thrust as the aircraft departs from an airport, and lower thrust as the aircraft approaches an airport.
  • Some aircraft engine noise can be partially suppressed at the engine nacelle inlet and the exhaust nozzle and centerbody by noise absorbing structures. These structures can absorb acoustic energy by canceling acoustic reflected waves and/or converting acoustic energy into heat, and typically consist of a porous skin and three or more non-perforated walls to form one or more chambers.
  • porous skin and non-perforated walls of such chambers combine to form a plurality of Helmholtz resonators that resonate in response to certain sound frequencies or certain bands of frequencies, and cancel sound waves reflected between the porous face skin and non-perforated walls and/or subsequently convert sound energy to heat (via elastic or mechanical hysteresis caused by the resonant response of air within the resonator cavities and of the liner components), and thereby effectively absorb or dissipate at least a portion of generated engine noise.
  • An example of a sound-absorbing exhaust nozzle center plug is disclosed in U.S. Patent 7,784,283 .
  • a sound-absorbing exhaust center plug for an aircraft gas turbine engine comprising a center plug adapted for attachment within an exhaust nozzle of the engine.
  • the center plug comprises an outer skin, and at least one cavity within the center plug and the at least one cavity extending between a forward bulkhead and an aft bulkhead, where the aft bulkhead is canted inwardly.
  • the outer skin includes a plurality of outer skin openings providing an acoustic pathway through the outer skin and into the at least one cavity.
  • the inwardly canted aft bulkhead may extend from a radially outer edge radially inward in a forward direction.
  • the least one cavity may comprise a forward cavity and an aft cavity that is substantially aft of the forward cavity, and a wall separating the forward cavity from the aft cavity, the wall including a plurality of first openings therethrough.
  • the outer skin may include a forward skin portion substantially coinciding with an axial position of the forward cavity and an aft skin portion, and where the plurality of outer skin openings are in the forward skin portion.
  • the forward bulkhead may be canted inwardly.
  • the center plug may comprise an inner skin forming a substantially hollow center portion of the plug body.
  • a noise-absorbing center plug for a jet engine exhaust nozzle.
  • the noise-absorbing center plug comprises a center plug adapted for assembly within the exhaust nozzle, and a plurality of walls defining a plurality of circumferentially spaced resonator cavities within the center body where the plurality of circumferentially spaced resonator cavities extend from a forward bulkhead to an aft bulkhead that is canted inwardly.
  • the noise-absorbing center plug also comprises at least one wall separating at least one of the resonator cavities into a forward sub-cavity and an aft sub-cavity, the wall including a plurality of first openings therethrough.
  • the aft bulkhead may extend from a radially outer edge radially inward in a forward direction.
  • the noise-absorbing center plug may include an outer skin at least partially enclosing the circumferentially spaced resonator cavities.
  • the outer skin may include a plurality of second openings extending therethrough, the plurality of second openings providing acoustic pathways through the outer skin and into at least one forward sub-cavity.
  • the forward bulkhead may be canted inwardly.
  • the outer skin may include a plurality of second openings extending therethrough and a plurality of third openings extending therethrough, the plurality of second openings providing acoustic pathways through the outer skin and into at least one forward sub-cavity, and the plurality of third openings providing acoustic pathways through the outer skin and into at least one aft sub-cavity.
  • the noise-absorbing center plug may also include an inner skin forming a substantially open center cavity within the center plug.
  • a noise-absorbing exhaust nozzle center plug for an aircraft gas turbine engine comprising a center plug having a first longitudinal axis.
  • the plug body comprises an outer skin surrounding the center plug, an inner skin, the outer skin and the inner skin forming a substantially annular space therebetween axially extending between a forward bulkhead and inwardly canted aft bulkhead, and a plurality of walls separating the annular space into a plurality of substantially longitudinally-extending cavities.
  • the center plug is configured for assembly within an exhaust nozzle of the aircraft gas turbine engine.
  • the outer skin may include a second plurality of openings extending therethrough, the second plurality of openings forming a plurality of acoustic pathways through the outer skin and into at least a portion of the longitudinally-extending cavities.
  • the forward and aft cavities may each have a largest dimension that extends in a substantially forward-aft direction.
  • the inwardly canted aft bulkhead may extend from a radially outer edge radially inward in a forward direction.
  • FIG. 1 shows one embodiment of a combustor exhaust portion 30 of an aircraft gas turbine engine.
  • the combustor exhaust portion 30 includes an exhaust nozzle 32 and an exhaust centerbody 37.
  • the centerbody 37 can be formed in two sections including an acoustically treated forward portion (referred to herein as a "center plug") 100, and an aft cone portion 38.
  • the exhaust nozzle 32 and the center plug 100 cooperate to form an annulus 36 through which exhaust gasses from the engine's combustor exit the exhaust portion 30 to generate forward thrust.
  • the center plug 100 and the cone portion 38 of the centerbody 37 are connected along a circumferential seam 34 at the aft end of the center plug 100.
  • FIG. 1 shows one embodiment of a combustor exhaust portion 30 of an aircraft gas turbine engine.
  • the combustor exhaust portion 30 includes an exhaust nozzle 32 and an exhaust centerbody 37.
  • the centerbody 37 can be formed in two sections including an acoustically treated forward portion (referred to herein as a
  • the aft portion of the center plug 100 and the attached cone portion 38 extend aft from the aft end of the nozzle 32.
  • the outer surfaces of the center plug 100 and the cone 38 combine to form a flow control surface that substantially prevents recirculation of the exiting exhaust gasses, and facilitates convergence of the exhaust gasses as they exit the annulus 36.
  • the center plug 100 of the centerbody 37 forms a transition between the aft end of a turbine rotor (not shown) located just inside the combustor exhaust portion 30, and the cone 38.
  • the center plug 100 and the cone 38 may have hollow center portions (not shown in FIG. 1 ) that permit cooling air to pass from an intake 39 at the aft tip of the cone to internal portions of the engine, and/or house instrumentation, wiring, or the like, etc.
  • FIG. 2 shows one embodiment of an acoustically treated center plug 100.
  • the center plug 100 includes an outer skin 102 having an aerodynamic outer contour.
  • the outer skin 102 is seamlessly constructed such that the center plug 100 has a substantially smooth outer surface.
  • the center plug 100 can have a forward flanged end 104 configured for attachment to a casing proximate to the aft end of a turbine rotor (not shown), and an aft flanged end 106 configured for attachment to a cone 38 like that shown in FIG. 1 .
  • the outer skin 102 can include at least one acoustically permeable portion 108.
  • the acoustically permeable portion 108 can be formed by a plurality of spaced openings 110 that extend through the outer skin 102.
  • the acoustically permeable portion 108 is located on a forward portion of the outer skin 102, and extends around substantially the entire circumference of the forward portion of the outer skin.
  • the perforated portion 108 may coincide with a forward portion of one or more forward resonator cavities 132b ( FIG. 5 ).
  • the perforated portion 108 may coincide with an aft portion of the one or more forward resonator cavities 132b. Further details of the acoustically permeable portion 108 are described below.
  • the center plug 100 includes a substantially open center 122 bounded by an inner skin 120.
  • the inner skin 120 may be constructed in segments, or in a single piece.
  • the inner skin 120 has a substantially cylindrical shape, and is centered along a central longitudinal axis of the center plug 100.
  • An imperforate forward bulkhead 112 extends between the inner skin 120 and the outer skin 102 proximate to the forward flange 104.
  • the forward bulkhead 112 is not necessarily perpendicular to the longitudinal axis. It may be formed so the inner portion of the bulkhead is aft of the outer portion, which will be described below as canted inwardly.
  • FIGs. 4 and 5 show the center plug 100 with the outer skin 102 removed.
  • an imperforate aft bulkhead 160 is not necessarily perpendicular to the longitudinal axis. It may be formed so the inner portion of the bulkhead is forward of the outer portion, which will be described below as canted inwardly.
  • the aft bulkhead 160 is located proximate to the aft flange 106 inwardly and extends between the inner skin 120 and the outer skin (not shown in FIG. 4 ).
  • a perforated intermediate wall or bulkhead 130 is located intermediate to the forward bulkhead 112 and the aft bulkhead 160.
  • the intermediate bulkhead 130 divides the region bounded by the inner skin 120, the forward bulkhead 112, the aft bulkhead 160, and the outer skin 102 (not shown in FIGs. 4 and 5 ) into a forward annular chamber 132 and an aft annular chamber 134.
  • the perforated intermediate bulkhead 130 provides structural support to the outer skin 102, and can prevent or at least reduce non-planar sound wave modes from propagating between the forward and aft chambers 132, 134.
  • a plurality of imperforate forward baffles 140a-140d can divide the forward annular chamber 132 into a plurality of forward resonator cavities 132a-132d.
  • a plurality of imperforate aft baffles 150a-150d similarly can divide the aft annular chamber 134 into a plurality of aft resonator cavities 134a-134d.
  • four forward baffles 140a-140d divide the forward chamber 132 into four forward resonator cavities 132a-132d having substantially equal volumes and dimensions.
  • each of the forward baffles 140a-140d is axially aligned with one of the aft baffles 150a-150d.
  • each of the baffles 140a-140d (and each of the axially aligned aft baffles 150a-150d) extends substantially radially outward from the central longitudinal axis "x-x" of the center plug 100.
  • the forward and aft baffles 140a-140d and 150a-150d act to at least partially prevent sound waves that enter the resonator cavities 132a-132d and 134a-134d from propagating in a circumferential direction between adjacent cavities, and helps to restrict the sound waves to lower order modes of oscillation and propagation, such as plane wave modes.
  • the perforated bulkhead 130 may be removed so as not to longitudinally divide the cavity.
  • the inwardly canted aft bulkhead 160 allows for improved maintenance access.
  • gaps 145a-145d may exist between the outermost edges of the forward baffles 140a-140d and the outer skin 102 in order to accommodate differential thermal expansion between the baffles 140a-140d and the outer skin 102 during thermal transient conditions.
  • gaps 155a-155d may exist between the outermost edges of the aft baffles 150a-150d and the outer skin 102 in order to accommodate differential thermal expansion between the baffles 150a-150d and the outer skin 102 during thermal transients.
  • gaps 145a-145d, 155a-155b do not substantially adversely affect the ability of the resonator cavities 132a-132d and 134a-134d to dissipate targeted low-frequency sound energy.
  • FIG. 7 shows a partial longitudinal cross section of the center plug 100 described above. Also shown in phantom lines in FIG. 7 is an exhaust nozzle 32 that in conjunction with the outer skin 102 of the center plug 100 defines an annular exhaust duct 36. As indicated by arrows "A" in FIG. 7 , exhaust gases from the engine combustor pass through the annular duct 36 and create grazing flow that is substantially parallel to the outer surface of the perforated portion 108 of the outer skin 102.
  • the velocity of the grazing exhaust flow at the perforated portion 108 typically can be about Mach 0.2 to about Mach 0.4, or higher.
  • Sound waves from the grazing flow "A" propagate through the perforated portion 108 of the outer skin 102 and into the forward resonator cavity 132b in a direction generally indicated by arrows "B".
  • arrows "B" are substantially perpendicular to the perforated portion 108 of the outer skin 102.
  • the perforated portion 108 of the outer skin 102 can have a POA of about 20 percent to about 25 percent.
  • the perforated portion 108 may have a higher or lower POA depending upon the desired acoustic impedance and aerodynamic performance of the perforated portion 108.
  • the perforated portion 108 of the outer skin has a substantially uniform thickness of about 0.02 inches (0.51 mm) to about 0.05 inches (1.27 mm), and includes a plurality of spaced openings 110 extending therethrough.
  • the openings 110 can have a diameter of about 0.005 inches (0.13 mm) to about 0.050 inches (1.27 mm), or any other desired size. In one embodiment, the openings are about 0.02 inches (0.51 mm) in diameter.
  • These small-diameter openings 110 have an insubstantial effect upon the aerodynamic performance of the outer skin 102, and may be formed in the outer skin 102 by laser drilling, for example. Such small-diameter openings 110 are preferable over larger punched holes that typically range from about 0.04 inches (1.02 mm) to about 0.08 inches (2.03 mm) in diameter.
  • the perforated intermediate bulkhead 130 can have a POA of about 30 percent to about 40 percent.
  • the intermediate bulkhead 130 may have a higher or lower POA depending upon the desired acoustic impedance of the bulkhead 130.
  • the intermediate bulkhead 130 is constructed of an aerospace grade titanium alloy, has a substantially uniform thickness of about for example 0.032 inches (0.813 mm), and includes a plurality of spaced openings 136 extending therethrough.
  • the openings 136 have a diameter of about 0.25 inches (6.35 mm).
  • the openings 136 can have a different diameter to provide a different POA and/or spacing of the openings 136, if desired.
  • the intermediate bulkhead 130 may provide structural support to the outer skin 102.
  • the largest dimensions (L 1 , L 2 ) of the resonator cavities 132b, 134b extend in a direction that is substantially parallel to the longitudinal axis of the center plug.
  • FIG. 7 shows only one forward cavity 132b and one aft cavity 134b, it should be understood that other circumferentially spaced sets of aligned forward and aft cavities also can exist in the center plug 100 as shown in FIGs. 4 and 5 , for example.
  • the axially aligned resonator cavities 132b and 134b make effective use of the available longitudinal extent of the center plug 10, such that the effective maximum lengths or depths of the forward and aft resonator cavities (L 1 , L 2 ) and their combined length "L 3 " are substantially greater than they otherwise would be if the cavities were of the conventional non-folding type described above.
  • the relatively deep forward and aft resonator cavities 132a-132d and 134a-134d of the center plug 100 can be tuned to resonantly respond to relatively low-frequency sound energy less than about 800 Hz, and thus dissipate sound energy at such frequencies.
  • the resonator cavities 132a-132d and 134a-134d are configured to dissipate sound energy between about 400 Hz and about 630 Hz. Accordingly, such a center plug 100 can be effective in dissipating at least some low-frequency sound energy emanating from an aircraft gas turbine engine's combustor, especially at and between idle and approach engine speeds.
  • the intermediate bulkhead 130 may be omitted.
  • the center plug 100 shown in FIG. 8 would include a single cavity extending between the forward bulkhead 112 and the inward canted aft bulkhead 160 (either of which or both may be built at an angle other than perpendicular to the longitudinal axis).
  • FIG. 8 shows another embodiment of a hot nozzle center plug 200.
  • the center plug 200 includes a plurality of circumferentially spaced forward resonator cavities 232, and a plurality of circumferentially spaced aft resonator cavities 234.
  • the forward and aft cavities 232, 234 are bounded by an inner skin 220, an outer skin 202, a forward imperforate bulkhead 212 proximate to a forward flange 204, and an aft imperforate bulkhead 260 proximate to an aft flange 206.
  • the bulkhead 260 may be canted inwardly.
  • An imperforate intermediate bulkhead 230 separates the forward and aft cavities 232, 234.
  • the imperforate intermediate bulkhead 230 substantially prevents sound waves from propagating between the forward and aft cavities 232, 234.
  • Sound waves from the annular exhaust duct 36 propagate through a forward perforated portion 208a of the outer skin 202 that coincides with a forward portion of the forward cavities 232 (as indicated by arrows B in FIG. 8 ), and thus enter the forward cavities 232.
  • Sound waves also propagate through an aft perforated portion 208b of the outer skin 202 that coincides with a forward portion of the aft cavities 234 (as indicated by arrows B' in FIG. 8 ), and thus enter aft cavities 234.
  • the forward and aft perforated portions 208a, 208b form separate perforated bands that extend around substantially the full circumference of the outer skin 202.
  • the positions of the perforated portions 208a, 208b shown in FIG. 8 coincide with forward portions of their respective cavities 232, 234, it should be understood that one or both of the perforated portions 208a, 208b can alternatively be positioned to coincide with an aft or other portion of its respective cavity 232, 234.
  • the positions of the perforated portions 208a, 208b may be selected based upon the predicted or measured velocities of grazing exhaust flows at various axial locations along the exhaust duct 36, for example.
  • the forward perforated portion 208a of the outer skin 202 includes a plurality of first openings 210a extending therethrough.
  • the aft perforated portion 208b of the outer skin 202 includes a plurality of second openings 210b extending therethrough.
  • the sound waves respectively propagate within the cavities 232, 234 in directions C and C', which are substantially parallel to the central axis of the center plug 200, and are non-parallel to the entry directions B and B'.
  • the forward and aft perforated portions 208a, 208b can each have a POA of about 20 percent to about 30 percent.
  • the forward and aft cavities 232, 234 each can have a cavity depth of about 10 inches, and may have volumes of about 900 cubic inches (0.01475 cubic metres) and about 700 cubic inches (0.01147 cubic metres), respectively.
  • the effective cavity depths and relative volumes of the forward and aft cavities 232, 234 can be varied to tune the cavities 232, 234 to one or more target frequencies.
  • the relatively deep longitudinal extent of the forward and aft folding resonator cavities 232, 234 permits the cavities to be tuned to dissipate sound energy at frequencies less than about 800 Hz. In one embodiment, the cavities 232, 234 can be tuned to dissipate sound energy at a peak frequency of about 500 Hz.
  • FIG. 9 shows a center plug 300 having substantially non-folding forward and aft resonator cavities 332, 334.
  • non-folding resonator cavities typically are less effective at dissipating low-frequency sound energy of 800 Hz or less, but can be useful in certain applications.
  • the center plug 300 includes a plurality of circumferentially spaced forward resonator cavities 332, and a plurality of circumferentially spaced aft resonator cavities 334.
  • the forward and aft cavities 332, 334 are bounded by an inner skin 320, an outer skin 302, a forward imperforate canted bulkhead 312 proximate to a forward flange 304, and an aft imperforate inwardly canted bulkhead 360 proximate to an aft flange 306.
  • An imperforate intermediate bulkhead 330 separates the forward and aft cavities 332, 334.
  • the imperforate intermediate bulkhead 330 substantially prevents sound waves from propagating between the forward and aft cavities 332, 334.
  • substantially the full extent of the outer skin 302 between the forward bulkhead 312 and aft bulkhead 360 can include a plurality of spaced openings 310 extending therethrough.
  • the bulkheads 312, 360 may be canted inwardly.
  • the perforated portion of the outer skin 302 is substantially more extensive than the relatively short axial extents of the perforated portions 108, 208a, 208b of the center plugs 100, 200 shown in FIGs. 7 and 8 .
  • the perforated portions of the outer skin 302 may have a POA of about 20 percent to about 30 percent.
  • the openings 310 permit sound waves from the annular exhaust duct 36 to propagate through the outer skin 302, into the forward cavities 332 (as indicated by arrows B in FIG. 9 ), and into the aft cavities 334 (as indicated by arrows B' in FIG. 9 ).
  • the sound waves generally propagate within the cavities 332, 334 in directions C and C', which are substantially parallel to the entry directions B and B'.
  • the forward and aft cavities 332, 334 are of the non-folding type, and have relatively shallow effective cavity depths as compared to the cavities of the center plugs 100, 200 described above.
  • the forward resonator cavities 332 may each have an effective depth of about 5 inches (127 mm) and a volume of about cubic 900 inches (0.01475 cubic metres), and the aft resonator cavities 334 each have an effective depth of about 4 inches (101.6 mm) and a volume of about 700 cubic inches (0.01147 cubic metres). Because of the relatively shallow effective depths of the forward and aft non-folding resonator cavities 332, 334, the cavities 332, 334 only can be effectively tuned to dissipate sound energy at frequencies of about 1000 Hz or greater. Accordingly, such a center plug 300 may be less capable of dissipating low-frequency sound energy of the type produced by an aircraft gas turbine engine's combustor, but can be useful in certain applications.
  • FIG. 10 shows another embodiment of an acoustically treated center plug 400.
  • the center plug 400 can be constructed substantially the same as the center plug 100 described above, but with additional high-frequency acoustic treatment along aft portions of the outer skin 402.
  • the outer skin can include a forward perforated portion 408a that can include a plurality of spaced forward openings 410a extending therethrough, and an aft perforated portion 408b that can include a plurality of spaced openings 410b extending therethrough.
  • the spaced forward openings 410a permit sound waves to enter a large forward folding cavity 432 bounded by the outer skin 402, an imperforate forward bulkhead 412 that is canted inwardly, a perforated intermediate bulkhead 430, and an inner skin 420.
  • the perforated intermediate bulkhead 430 permits sound waves to propagate through the bulkhead 430 and into a large aft folding cavity 434. Accordingly, the large folding cavities 432, 434 of the center plug 400 can be tuned to absorb and dissipate relatively low-frequency sound energy at less than about 800 Hz.
  • the aft perforated portion 408b of the outer skin 402 substantially coincides with the extent of a cellular core 480 affixed along the inside surface of the outer skin 402. As shown in FIG. 10 , the aft perforated portion 408b, cellular core, and an imperforate back skin 482 combine to form a non-folding acoustic liner 490 of a type described above.
  • the acoustic liner 490 may be of the single-degree-of-freedom type as shown in FIG. 10 , or can be of the multiple-degree-of-freedom type.
  • the relatively shallow, small-volume resonator cavities of the acoustic liner 490 can be tuned to absorb and dissipate high frequency sound energy within the sound spectrum found proximate to the exhaust nozzle center plug 400. Accordingly, in this embodiment, the center plug 400 is capable of absorbing/dissipating at least some relatively low frequency exhaust noise, and at least some relatively high-frequency exhaust noise.
  • the outer skins 102, 202, 302, 402, inner skins 120, 220, 320, 420, forward bulkheads 112, 212, 312, 412, inwardly canted aft bulkheads 160, 260, 360, 460, intermediate bulkheads 130, 230, 330, 430, forward baffles 140a-140d, and aft baffles 150a-150d can be constructed of metal alloy sheet capable of withstanding temperatures greater than about 1230 degrees F (666 degrees C).
  • each of these components may by constructed of a high temperature aerospace grade titanium alloy, such as Ti-6-2-4-2, or the like.
  • the various components can be constructed of different materials depending upon the operating temperatures and structural requirements for each component.
  • the various components of the center plug 100, 200, 300, 400 can be joined by any suitable method or combination of methods, including welding and joining with fasteners, such as screws or rivets.
  • Inwardly canting the aft bulkhead provides improved maintenance access. Canting the aft bulkhead either inward or outward provides options for tuning the centerbody volume to reduce unwanted frequencies.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
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  • Aviation & Aerospace Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Exhaust Silencers (AREA)
EP19197404.7A 2018-09-14 2019-09-13 Corps central de cavité acoustique profonde Ceased EP3624111A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US16/131,420 US11136942B2 (en) 2018-09-14 2018-09-14 Acoustic deep cavity centerbody

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EP3624111A1 true EP3624111A1 (fr) 2020-03-18

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WO2023099852A1 (fr) * 2021-12-03 2023-06-08 Safran Nacelles Ensemble pour cone d'ejection de turbomachine d'aeronef
EP4332360A3 (fr) * 2022-09-02 2024-05-22 Rohr, Inc. Ensemble corps central d'échappement
EP4397847A1 (fr) * 2023-01-03 2024-07-10 Rohr, Inc. Corps central d'échappement de moteur à atténuation acoustique

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US11428191B1 (en) * 2021-04-30 2022-08-30 Rhor, Inc. Acoustic zoned system for turbofan engine exhaust application
US11867077B2 (en) 2021-06-07 2024-01-09 Rohr, Inc. Acoustic structure with floating interior skin
US12078125B2 (en) * 2021-09-13 2024-09-03 Rohr, Inc. Low-frequency acoustic center body
US11976597B2 (en) * 2021-09-13 2024-05-07 Rohr, Inc. Low-frequency acoustic center body

Citations (3)

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